In widely used etching methods for etching a semiconductor device, a plasma from a plasma source is often supplemented by plasma generated by using an additional plasma generating apparatus so that the generated plasma diffuses toward the location of a wafer to be etched, thereby etching layers on the wafer. The diffusion technique is carried out with etching equipment used to produce highly integrated semiconductor devices. Such equipment includes electron cyclotron resonance etchers, inductively coupled plasma etchers and helicon wave plasma etchers, all of which are characterized as low pressure, high density plasma equipment.
However, when diffusing plasma in order to move the plasma generated from an extra plasma source, plasma density rapidly lowers in the neighborhood of the wafer to be etched due to the diffusion of the plasma. This is true even though the plasma is generated at high densities. Also, since at the time of diffusion the mobility of electrons is more than 10.sup.3 times greater than that of ions, the number of electrons lost from the plasma is greater than that of lost ions, thereby raising the potential of the plasma. In order to prevent this phenomenon, the conventional technique is to install multiple permanent magnets around the diffusion chamber to maintain the plasma density.
FIGS. 1A and 1B are a perspective view and a plan view respectively, of a conventional plasma diffusion chamber. Reference numbers 10 and 12 denote respectively, a diffusion chamber wall and permanent multi-magnets attached to the chamber wall. However, with conventional methods, at the location indicated by reference number 14, the direction of the magnetic field is on a plane parallel to the chamber wall. As a result, the reflection of the plasma by the magnetic field is fully realized. In contrast the magnetic flux is configured in a direction perpendicular to the surface of the chamber at the location indicated by reference number 16. As a result the plasma proceeds along the direction of the magnetic flux thereby accelerating the attachment of polymer to the plasma chamber wall. FIG. 2 is a photograph showing the polymer attached to the chamber wall as a result of using conventional methods. The polymer attached to the chamber wall becomes a source of dust during the etching process. Consequently, the yield of the etched semiconductor devices is lowered and the operation rate of the equipment and its life span are reduced.